What problem does it solve?
Quick mental arithmetic exercises both processing speed and basic numerical fluency. The adaptive-difficulty version is more useful than a fixed list — it keeps you near your ceiling, where learning is most efficient.
Solve arithmetic as fast as you can. Difficulty adapts — if you're crushing it, the numbers grow; if you're stumbling, they shrink.
What makes this one different
We log per-operation accuracy: + − ×. Most people show uneven profiles — solid at addition but slower at multiplication, or vice versa. That profile is more informative than a single overall score.
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Quick mental arithmetic exercises both processing speed and basic numerical fluency. The adaptive-difficulty version is more useful than a fixed list — it keeps you near your ceiling, where learning is most efficient.
Score depends a lot on level. A score of 25 at level 3 is roughly equivalent to 20 at level 5. Track the score-per-level, not raw score.
Per-operation bars reveal your weak spot. Most adults are weakest at × because of the times-table dependency.
Exact match. We don't accept approximate answers because the goal is fluency, not estimation.
We cap × at 12×12 because beyond that the task shifts from fluency to calculation. We want to keep it mentally reachable.